Timed fuel injection system



Patented July 25, 1950 9 Claims.

(Granted under the act of March 3,1883, as

amended April 30,

' during high power operation.

A'still further object of the present invention is the provision of means for correcting metering suction that will compensate for changesin air.

density, thus making metering suction vary as the square of mass flow.

with the above and other objects in view the invention consists of certain novel details of construction and combination of parts hereinafter fully described and claimed, it being understood that various modifications may be resorted to without departing from the spirit and scope ofthe invention and the appended claims.

I Figure 1 is a sectional view of one' form of the device made in accordance with. the present invention. I

Figure 2 fllustrates a modification of the depending portion and showing a governor for controlling the valve stem in response to speed variations'. I

Referring to the drawings the numeral l represents a housing having a depending cylindrical portion I l and within the housing I0 are portions I2 and I3 all being integral with the housing. The

ends of the housing are provided with closure plates it that are secured'to the housing by bolts l5',"the end of the depending portion II or valve body also being provided with a closure plate It that is secured thereto by bolts II. The portion ii of the housing is provided with a tapering wall ll midway the ends, and centrally of the wall l8 thereis an orifice Iii that serves as a'metering jet.

The-wall i8 divides the'portion l3 into chambers 20 andll Interposed between the wallsof portions l2 andl3 is a valve '22 having'a wall 23 midway its ends and provided withan orifice or bleed port 24. Connected to the wall 23 is one end of rods 25 and 26, the opposite end of rod 25 carrying adiaphragm 21, 'theopposite end of rod 26 carrying a diaphragm; the diaphragm's being in:sp'acedrelation"from the ends of portions l2 and I3 and in spaced relation from the ends of the closure plates it; thus formin'gchambers Hand 30. The. housing l0 is provided with a threaded fuel inlet it that "communicates with "a channel;

32 and the chamber 20. The body It has an annular shoulder 53, the end of which is closed by a plate 34 that is secured to the shoulder. by bolts 15. Within the shoulder 83 is a diaphragm 36 that is connected to one end of a valve stem 31,

5 the opposite end oi the stem carrying avalve .35

that engages a valve seat oi a bore 39 in the housing 10, the bore communicating with the chamber 2| and channel 32. The diaphragm 35 is in spaced relation from the plate 54 thus forming a chamber 40, and interposed between the plate 34 and the diaphragm 36 is a. spring II that holdsthe valve 38 inithe valve seat. A bleed opening 42 is also provided in the housing and this opening communicates with chamber 2| and chamber 40. The chamber 29 communicates with a throttle body through an impact tube 43, having a suitable metering device 68; and chamber 30, with the low pressure point of a venturi 44 by a conduit". Chambers 29 and 30 are provided with bleedopenings 45 and 41 respectively and they are connected by a conduit 48, having arestricted portion 48'. The portion I2, of the, housing [0 is provided with a channel or chamber 49 havinga portion in the depending portion I i that communicates with a horizontal channel 50. Within the depending portion ll there is mounted a rotary valve 5| that is driven by a pump 52 which is 'driven by the engine. The rotary valve 5! is driven at one .half engine speed for a four stroke cycle engine,

and at engine speed for a two stroke cycle engine. Pump 52 is connected to the rotary valve 5| by a shaft 53. The rotary valve 5| is balanced in the depending portion H by a spring 55. The depending portion I l is provided with horizontal bores 55 and 56 that are diametrically opposite to each other, bore 55'being in communication with. a conduit 51 that is provided at its lower. end,

with a spring controlled valve 5|. Bore 55 is like- 6| adapted foralignment' with bores "and 56.

Adjacent the lower end of the. die pendingportion II is a horizontal bore 52 that communicates with the spring chamber 53 Housing I0 is prochamber 2i, and thischamber is 'in' communication with chamber 6: through conduit 55. If desireda governor as illustrated in Figure 2 maybe mounted on he-ens bi shaft". as shownin li'igure 2 tl e d'epending portioniil has its lower'endtl enlarged to allow'free movement of the pivoted weights".

sure enters the inlet ti and into chamber 2| and vided with a bore, N, that communicatesfwith 1 In the operation or the "device fuel under pres 3 then passes through metering orifice or let I! into chamber 2 I.

The pressure in inlet 3| is limited at the high end by what diaphragms 21 and 29 will take before danger of rupturing. The low limit will be determined by the pressure necessary in passage II high enough to control cavitation at pump 52. This is a function of design and a specific figure cannot be given.

The low limit in chamber 29 or at inlet ll must be low limit in chamber 2| plus maximum head. which is maximum pressure differential across jet l9. This is equal to maximum metering suction which is difference in pressure in chambers 29 and 90. With a Venturi impact tube arrangement as shown the metering suction will not exceed 100 inches of H20 or about 3 lbs. Therefore for maximum output with good design lbs. pressure at ll would be sufiicient inlet pressure, although or more lbs. would probably be better. For part throttle and idle the requirement for pressure would be considerably less than at full throttle.

The amount of fuel delivered from nozzles BI and 90 will be a function of nozzle opening pressure and the pressure in lines 51 and 58 respectively. The pressure in line 51 or 99 is increased to the pressure in chamber 49 when port Cl and port 55 or 56 are in communication. They are timed to deliver fuel during correct part of cycle by positively timing and driving valve 5|. Through pump 52 the port 4| in valve 5| is made to give increasing area exposure to port 55 as the valve 5| is moved down against spring 54. Therefore as the load on the engine is increased the need for fuel is increased and the pressure in 49 will have to be increased. Also, as the speed increases the period of time that ports 55 and 9| are in communication is shortened and therefore it will be necessary to increase the pressure in 49 in order to deliver the required amount of fuel out to the nozzles. This is accomplished by varying the pressure in chamber 49 to give the required amount of fuel to the engine. The pressure in chamber 49 is determined by the discharge through nozzle 58 and the quantity of fuel from the pump 52 and area of port 24 which is open.

With port 24 closed the pump 52 will build up pressure in chamber 49 since it is designed to have a capacity greater than that required by the engine at full throttle. When the pressure in chamber 49 starts to go above pressure required to give the engine the fuel it needs at that moment, valve 24 will open to the point of maintaining the required pressure by by-passing the excess fuel from the pump 52 back into chamber 2| which feeds the inlet to the pump. Therefore the amount of fuel delivered by the nozzles will be the amount taken from chamber 2| by pump 92 less amount returned by port 24. The amount of fuel flowing into chamber 2| will be equal to fuel being delivered to the engine. The fuel entering chamber 2| is measured by orifice 9 since the amount of fuel flowing varies as the square root of metering head, and since the pressure in chamber 2k is held relatively constant by the engine pump. The pressure in chamber 2| will be reduced by the pump 52 to the point where metering head is equal to metering suction. Metering head is the pressure drop across orifice i9 and metering suction is the difference between pressures in chambers 29 and it.

Since metering suction is for all practical put-- 4 poses equal to the square root of mass air flow and metering head is equal to the square root of fuel flow, the fuel air ratio will be a constant for all air flows. But. since in the high power range an increase in fuel air ratio is needed the enrichment valve 99, its diaphragm 38 and spring 4| are added. Diaphragm action is such that as metering head increases it will reach a point where it will overbalance spring 4| and valve 39 will open allowing an additional supply of fuel to fiow into chamber 2|.

The pressure in chamber 49 is many times higher than in chamber 43 therefore there will be leakage into chamber 93. This has to have an outlet (92) or the pressure in 89 would build up to that in chamber 49 and valve 9| would not operate. Pipe '5 could be runback to the fuel tank instead of into chamber 2| but then all metered fuel would not be delivered to the engine. Passage 5 will have very little eifect on the position of valve BI and almost none on the operation.

The element I9 is for altitude and temperature compensation and is used on several conventional aircraft carburetors. It may consist, for example and as shown in U. S. Patent No. 2,410,733 of a calibrated needle operable by a bellows to vary the metering suction in response to barometric and temperature changes. The calibration is made very effective through use of a correct orifice 49' in the pipe 48. Without this orifice, any variation in the compensator 64 could not aifect the pressure in chamber 29 because it then would be a static pressure in the absence of flow from 2-9 to chamber 39.

While the form of mechanism herein shown and described constitutes a preferred form of embodiment of the present invention, it is to be understood that other forms might be adopted.

all coming within the scope of the claims, which ,1

follow.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. Fuel supply system for internal combustion engines having an intake manifold with a venturi followed by a throttle comprising a pressure controlled casing having chambers in its ends bounded by internal diaphragms connected to operate a bleed valve by the differential pressure in said chambers, one of said chambers being connected by an impact tube to said manifold at a point ahead of the venturi, the inner faces of said diaphragms forming a portion of the walls for a fuel supply chamber and a fuel intake chamber, there being a restricted orifice between said chambers and a by-pass valve between said chambers operated in response to a reduction in pressure in said intake chamber to open and permit fluid to by-pass said orifice from said supply chamber to said intake chamher, a positive displacement pump driven by said internal combustion engine for delivering fuel from said intake chamber to the engine through a multiple injection system, said bleed valve controlling an orifice between the delivery side of said pump and said intake chamber to return excess fuel to said intake chamber in response to differential pressure in said end chambers and in said supply and intake chambers.

2. Fuel supply system for internal combustion engines having an intake manifold with a ven- 5 turi followed by a throttle comprising a pressure controlledcasing having chambers in its ends bounded by internal diaphragms connected to operate a'bleed valve by the differential pressure in said chambers, one of said chambers being connected to the manifold ahead of the throttle, the inner faces of said diaphragms forming a portion of the walls for a fuel supply chamber and a fuel intake chamber, there being a restricted orifice between said chambers and a by-pass valve between said chambers operated in response to a reduction in pressure in said intake chamber to open and permit fiuid to bypass said orifice from said supply chamber to said intake chamber, a positive displacement pump driven by said internal combustion engine for delivering fuel from said intake chamber to an outlet chamber, a distributor valve in said outlet chamber connected for rotation by said pump, said valve being ax ally adjustable by pressure in said outlet chamber acting against a control spring and the pressure in said intake chamber.

3. Fuel supply system for internal combustion engines having an intake manifold with a venturi followed by a throttle comprising a pressure controlled casing having chambers in its ends bounded by internal diaphragms connected to operate a bleed valve by the differential pressure in said chambers, one of said chambers being connected to the manifold ahead of the throttle, the inner faces of said diaphragms forming a portion of the walls for a fuel supply chamber and a fuel intake chamber, there being a restricted orifice between said chambers and a by-pass valve between said chambers operated in response to a reduction in pressure in said intake chamber to open and permit fluid to bypass said orifice from said supply chamber to said intake chamber, a positive displacement pump driven by said internal combustion engine for delivering fuel from said intake chamber to the engine through a variable injection system, said bleed valvecontrolling an orifice between the delivery side of said pump and said intake chamber to return excess fuel to said intake chamber in response to differential pressure in said end chambers and in said supply and intake chambers, said end chambers being connected by a conduit.

4. Fuel supply system for internal combustion engines having an intake manifold with a venturi followed by a throttle comprising a pressure controlled casing having chambers in its ends bounded by internal diaphragms connected to operate a bleed valve by the differential pressure in said chambers, one of said chambers being connected to the manifold ahead of the throttle, the inner faces of said diaphragms forming a portion of the walls for a fuel supply chamber and a fuel intake chamber, there being a restricted orifice between said chambers and a lby-pass valve between said chambers operated in response to a reduction in pressure in said intake chamber 5. Fuel supply system for internal combustion engines having an intake manifold with a venturi followed'by a throttle comprising a pressure controlled casing having chambers in its ends bounded by internal diaphragms connected to operate a bleed valve by the differential pressure in said chambers, one of said chambers being connected to the manifold ahead of the throttle, the inner faces of said diaphragms forming a portion of the walls fora fuel supply chamber and a fuel intake chamber, there being a restricted orifice between said chambers and a by-pass valve between said chambers operated in response to a reduction in pressure in said intake chamber to open and permit fluid to by-pass said orifice from said supply chamber to said intake chamber, a positive displacement pump driven by said internal combustion engine for delivering fuel from said intake chamber to an outlet chamber, a distributor valve in said outlet chamber connected for rotation by said pump, said valve axially adjustable in response to speed variation and a governor mounted for rotation with said valve to control said adjustment.

6. In combination with a throttle tube having impact and Venturi tubes connected thereto, a closed casing having movable walls adjacent its ends forming impact and Venturi chambers, a stationary wall between said movable walls forming therewith fuel receiving and discharging chambers, a metering orifice extending through said stationary wall, a valve slidable in said stationary wall and having portions engaging the movable walls for operation by the latter, said casing having a fuel discharge passage containing a rotary timing valve and having two intersecting supply passages, a rotary pump in one of said supply passages, said slidable valve having a port in communication with said discharging chamber and shiftable into communication with the other supply passage, and means connected into said discharge passage to convey away the fuel metered through said timing valve.

7. In the combination defined in claim 6, said timing valve being cylindrical and hollow with one end exposed to the discharge fuel and also being slidable axially, yieldable means at the other end of said timing valve substantially balancing the pressure exerted by the discharged fuel, and said port opening laterally through the cylindrical wall of said timing valve.

8. In the combination defined in claim 6, means forming a separate connection between said fuel receiving and discharging chambers for automatically supplying additional fuel when it is required.

9. In the combination defined in claim 6, a compensator associated with said impact tube, and means having a restricting orifice interconnecting said impact and Venturi chambers.

HUGH S. ROBINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,402,332 Lee June 18, 1946 2,410,773 Chandler Nov. 5, 1946 FOREIGN PATENTS Number Country Date 852,446 France Oct. 30, 1939 

